1. Field of the Invention
The present invention relates to an apparatus for group control of a plurality of elevators moving in a single elevator shaft.
2. Background Art
A plurality of elevators installed side by side are usually operated through group control. In an ordinary elevator, as is well known, one car moves in one elevator shaft. In association with an increase in the height of recent buildings, as shown in FIG. 2, for example, moving a plurality of cars within a single elevator shaft has been proposed in order to improve the operating efficiency of the elevator and service to the user. In FIG. 2, two cars are moving within each of four elevator shafts; namely, cars A1 and A2 are moving within an elevator shaft #A; cars B1 and B2 are moving within an elevator shaft #B; cars C1 and C2 are moving within an elevator shaft #C; and cars D1 and D2 are moving within an elevator shaft #D.
The most significant point of difference between the case where group control is applied to an ordinary elevator in which one car moves within an elevator shaft and the case where a group control is applied to an elevator in which a plurality of cars move within a single elevator shaft is that the plurality of cars moving within a single elevator must be controlled so as to prevent a collision therebetween.
A group control system taking into consideration the aforementioned problem is described in Japanese Patent Application Laid-open No. Hei-8-133611, which provides a safety measure for preventing collision between the cars. Under this system, for each car there is designated a segment of the shaft into which another car is prohibited from entering, and the other car is controlled so as not to enter the designated segment.
In the group control apparatus that controls the elevators in which a plurality of cars move within each single elevator shaft, car entry prohibition segments are designated to thereby prevent a car from colliding with another. Therefore, such a group control apparatus may be said to be adequate in terms of preventing collision between cars, but must be said to be inadequate in terms of attaining more efficient group control.
The present invention has been conceived to solve the problem described above, and the object of the present invention is to provide an elevator group control apparatus which enables prevention of collision between a plurality of cars within each single elevator shaft and an improvement in operating efficiency.